Question

What are different classes of enzymes? Explain any two with the type of reaction they catalyse.

Answer 1

Different classes of enzymes

Enzymes are categorised into different classes on the basis of the reaction that they catalyze:

1. Oxidoreductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases

Oxidoreductases

• This class of enzymes catalyze oxidation reduction reaction between two substrates, S and S’.
• These reactions involve transfer of electrons/ H${}^{+}$ from one molecule to another.
• In these reactions, one compound is oxidised and the other is reduced.
• Examples of class oxidoreductases are dehydrogenase and peroxidase.

S reduced + S' oxidised $\stackrel{Oxidoreductase}{\to }$ S oxidised + S' reduced

Transferases

• These enzymes transfer a functional group G (other than hydrogen) from one donor molecule to an acceptor molecule.
• Examples include kinases, which transfer the phosphate group from high-energy, phosphate-donating molecules like ATP to specific substrates.

Substrate + ATP $\stackrel{Kinases}{\to }$ Substrate - Phosphate + ADP